Titanium base alloys



United States Patent TITANIUM BASE ALIiOYS Geofirey Thomas Harris, Sheflield, and Henry Cave Child, Rotherham, England No Drawing. Application June 2, 1958 Serial No. 738,955

Claims priority, application Great Britain February 4, 1958 19 Claims. (Cl. 75-1755) This invention relates to titanium base alloys, and is a continuation-in-part of our application Serial No. 548,235, filed November 21, 1955. The alloys concerned are alpha-titanium (hexagonal close-packed structure) an dhave good creep resistance at 400-500 C. and good forgeability.

It is known that alpha-titanium alloys are more likely to be more creep resistant due to their hexagonal closepacked structure than the body centre cubic structure beta alloys, While additions such as aluminum, tin, zirconium, oxygen and nitrogen are known to stabilize the alpha form of titanium, such simple alloys are difiicult to manipulate as they are stable alpha in the forging range. Also, the best creep resistance can, so far as we are aware, only be imparted to titanium alloys, as with other alloy systems, when suitable precipitation hardening phases are present.

According to this invention, titanium alloys contain all three of:

(a) One or more elements for the strengthening of solid solution of alpha-titanium,

(b) One or more beta-forming elements which do not form intermetallic compounds but which make the alloy duplex (i.e. alpha and beta phases) in the forging range, which is usually about 700 to about 1100 C, and

(0) One or more elements which form precipitation hardening compounds with titanium.

As stated above, examples of alpha-strengthening or stabilizing agents are aluminum, tin, zirconium, oxygen and nitrogen.

, 2,893,864 Patented July 7, 1959 The most readily available beta-forming element which does not form an intermetallic compound is molybdenum, but this may be replaced in whole or in part by one or more of the elements vanadium, niobium and tantalum.-

Any of the known elements which form precipitation hardening compounds with titanium may be used. EXT amples of suitable elements are silicon, chromium, manganese, boron, and beryllium. Iron can be tolerated so long as one of the above elements is present.

The following are suitable ranges for the three essential simultaneous additions to titanium for improved or optimum creep strength and ease of fabrication:

(a) Alpha-strengtheners.0ne or more of:

In this range, oxygen and nitrogen are shown as esseii tial because they are invariably present as impurities, oxygen being usually present between 0.1% to 0.2% and nitrogen about 0.1%. If oxygen-free or nitrogen-free alloys could be prepared they would be regarded as being within the scope of the invention so long as aluminum with or without tin and/ or zirconium were present within its or their respective ranges.

(b) Beta-formers.-One or more of:

Examples of alloys according to the invention are:

Composition in weight percent. Balance T1 and impurities Example No.

Al Sn Zr Mo V Nb Ta Si Cr Mn B Fe Be 2 4 4 0. 5 4 4 0. 1 0. 2 0. 2 4 4 0. 2 0. 4 0. 4 4 4 0.3 0. 6 0. 6 4 4 0. 4 0.8 0.8 4 2 4 0. 5 4 2 4 0. 5 1 4 2 4 2 4 2 4 0. 5 1 4 2 4 2 4 3 4 0. 5 4 2 5 4 0. 5 4 8 4 0. 5 2 10 4 0. 5 4 2 4 0. 5 0. l 4 2 4 0. 5 0. 4 2 4 0. 5 0. 5 4 2 4 0. 5 O. 25 4 2 4 0. 1 4 2 4 0. 5 0. 5 4 2 4 0. 1 4 2 4 0. 3 4 2 4 0. 4 4 2 4 0. 5 4 2 4 0. 6 4 2 4 0. 4 2 4 l 4 2 4 2 6 2 2 0. 5 6 4 0. 5

air

Composition in weight percent. Balance T1 and impurities Example No.

awn mm m F oauu m n w m m m e m mm m d T Md .m g M 0 e t "m h fl wt S .0 fih n m &02 6 m m o T m 1111 .m m u m am w m 3.. m. e u 0 m m n m m mam .m e P 0 e e n m 5.3 O O o m aw mh n I. Q n m W 3. n he 6W7 n P.m m In s w e a m w t s m 100 b V r. e n .UT 1 e u u n d m g P m w. o n B n u 0 m f O C %M 2 08 n m 8 m W W mo w mm e m cm t a m .m 0 0 0 0 0 F 001 mm m M m t mm m4 g. a 0 a e1 1 n mum m m m .1" B u n n e H S w .I m 0. m0 n n n u N b S e H p o m W we 0 n n n m m m m 1 m we m woman maamnwm mnmnmmaa mm m m am m m M m z 1 am? gm m m m .mfi .I mwm w MIR u m m MT) I" a m 3 1.00 w o n n m 0.... u n u m v m me 54. 5385 7472998 Pl 3 m m. n 14683Rw 5& -o 5024 0 E 55555 5%5555555555555555555 T 11 ullmw lulmmm llllmlmfioammwml w nbP nw rum 0000 01.000000000000000000000 tt mm .l mm M n n .16 u n n n m w E .m Wm mtm LLLI w u n u n n n w e n s.... 3 3 H .1 9 mm 1.21 n u u u n H mm w m mmmunmwma wwnummnmwwwmnmmammmm 1 m 0 .368 b m mm m e& m 0% M W m 1 N m m m wma m m u v: 5 f v m H m m m m w s mmnm uwunmu muonnso T m o m m m u m m e w w w 0000 00000 0 0 LL0 1 LL m m m. u n p Iv m 44 44 4 211822445 R M mm 1 M. m m m m m 0 t 5 u a n u u m m. mu m c nnmmmm mmmmmmm u n N m m mmmm r 15 n u u u m m m m 0 0 0000 00000 00 n N m z m m u 1 o m m m m m m m 2.2. e u 2 28142262222222222222222 m g T1 9 9172 6 n n S .m m pm m c 1wmmmnmm m e a Rm 0 m mmw 00 00 0000 0 M m n s s. .w m m mm 6 e C 0 m P m m g M10 1 m m S :m M W cm e S e .1 h o m a m n mu m m u S m r. m e a 4 U 1 ion a e W x r t s k i m m E .m m 1 1 T T TT 1 BT T T .m m H mm TTFRFRTTRRR Tm d.m P

The heat treatment used for the above tests was cooling from 900 C., ageing for 24 bouts at 500 Q, and air cooling.

cording to the invention which have 4% A1, 2% Sn and 4% Mo together with precipitation hardening additions with or without additional alpha-strengthener(s) and/or beta-former(s) Examples T. 289 and T. 293 can be compared with the following examples according to the invention: T. 156, T. 107 and T. 295. Example T. 290 can be compared with Examples T. 292 and T. 291 which are according to the invention. It will readily be observed that incorporation of a precipitation hardening addition or additions with or without additional alpha-strengthener(s) and/or beta-former(s) gives rise to markedly improved properties.

Alloys according to the invention may also contain carbon up to 2%, with a preferred upper limit of 1% and a preferred lower limit of 0.1%. It has been found that the room temperature tensile strength of the alloys is improved by the addition of carbon in the above range or preferred range. Any of the examples hereinbefore set forth can therefore contain, in addition to oxygen and/ or nitrogen, carbon within the above-stated range or preferred range and serve to improve the room temperature tensile strength of the alloys disclosed. For example, the effect of adding 0.2% carbon to thealloy according to Example T. 51 aforesaid is to improve the tensile properties thereof as follows: ultimate tensile stress 99.2 tons per square inch, elongation 9.9%, and reduction of area 16% We claim:

1. A creep resistant titanium alloy consisting of at least one alpha-strengthening element selected from the group consisting of about 4-6% aluminum and about 2% tin, at least one of the beta-forming elements selected from the group consisting of about 4% molybdenum and about 2% vanadium, a precipitation hardening element selected from the group consisting of about 0.1 to 0.5% silicon, and about 0.2 to 2% manganese, and the balance titanium and impurities.

2. A creep resistant titanium alloy consisting essentially of about 4% aluminum, about 2% tin, about 4% molybdenum, about 0.5% silicon, and the balance titanium and impurities.

3. A creep resistant titanium alloy consisting essentially of about 4% aluminum,- about 4% molybdenum, one or more of the precipitation hardening elements selected from the group consisting of about 0.1 to 0.5% silicon, and about 0.2 to 0.8% manganese, and the balance titanium and impurities.

4. A creep resistant titanium alloy consisting essentially of about 4% aluminum, about 2% tin, about 4% molybdenum, about 0.5 to 2% manganese, and the balance titanium and impurities.

5. A creep resistant titanium alloy consisting essentially of about 4% aluminum, about 4% molybdenum, about 2% tin, and the balance titanium and impurities.

6. A creep resistant titanium alloy consisting essentially of about 6% aluminum, about 2% tin, about 0.5% silicon, about 2% vanadium, and the balance titanium and impurities.

7. Creep resistant titanium alloys consisting essentially of 2-10% aluminum, 18% molybdenum, and 0.1- 2% silicon, balance titanium and impurities.

8. Alloys according to claim 7, containing in addition at least one of the alpha-strengthening elements selected from the group consisting of Percent Tin Up to 8 Zirconium Up to 10 9. Alloys according to claim 7, containing in addi tion at least one of the beta-forming elements selected from the group consisting of Percent Vanadium Up to 10 Niobium Up to 10 Tantalum Up to 10 10. Alloys according to claim 7, containing in addition at least one precipitation hardening element selected from the group consisting of Percent Manganese Up to 2 Boron Up to 0.5 Beryllium Up to 0.5

Percent Oxygen 0.02-0.3 Nitrogen 0.02-0.2 Carbon 0.1- 1

and the balance titanium.

13. A creep resistant titanium alloy consisting essentially of about 4% aluminum, about 2% tin, about 5% zirconium, about 4% molybdenum, about 0.5% silicon, and the balance titanium and impurities.

14. A creep resistant titanium alloy consisting essentially of about 4% aluminum, about 2% tin, about 4% molybdenum, about 0.5% silicon, about 0.1% boron, and the balance titanium and impurities.

15. A creep resistant titanium alloy consisting essentially of about 6% aluminum, about 4% molybdenum, about 0.5% silicon, and the balance titanium and impurities. I

16. A creep resistant titanium alloy consisting essentially of about 6% aluminum, about 2% tin, about 4% molybdenum, about 0.5% silicon, and the balance titanium and impurities.

17. A creep resistant titanium alloy consisting essentially of about 6% aluminum, about 5% zirconium, about 4% molybdenum, about 0.5% silicon, and the balance titanium and impurities.

18. A creep resistant titanium alloy consisting essentially of about 8% aluminum, about 4% molybdenum, about 0.5% silicon, and the balance titanium and impurifies.

19. A creep resistant titanium alloy consisting essentially of about 8% aluminum, about 2% tin, about 4% molybdenum, about 0.5% silicon, and the balance titanium and impurities.

References Cited in the file of this patent UNITED STATES PATENTS 2,810,643 Methe Oct. 22, 1957 

7. CREEP RESISTANT TITANIUM ALLOYS CONSISTING ESSENTIAL= LY OF 2-10% ALUMINUM, 1-8% MOLYBDENUM, AND 0.1= 2% SILICON, BALANCE TITANIUM AND IMPURITIES. 